Bob, Unless you can find a great deal, 350 feet of flat hose will cost nearly as much as the pump. The suction hose has to be fairly rigid. Flat hose won't work on the suction end.

You could check with an electric utility that puts in a lot of underground as in subdivisions. They don't like to splice any poly pipe shorter than about 150 feet, and it ends up as scrap to be dumped or recycled. A friend of mine got some 4 inch to do some irrigation, but he said it was so stiff he had to bury it to hold it from re rolling. The 2 inch is about as big as I can handle.